Method of and apparatus for preparing, feeding, and burning pulverized fuel



L. H. BERGMAN METHOD OF AND APPARATUS FOR PREPARING, FEEDING, ANDBURNING PULVERIZED FUEL April 1925.

Filed AprQl 14 1924s a in the claims.

Patented Apr. 7, 1925.

UNITED STATES PATENT OFFICE.

LABS H. BERG-MAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO RAYMOND BROS.ENGINEER- ING CO., OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

METHOD OF AND APPARATUS FOR PREPARING, FEEDING, AND BURNING PULVER- IZEDFUEL.

Application filed April 14, 1924. Serial No. 706,415.

To all whom it may concern:

Be it known that I, LABS H. BERGMAN, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Methods of and Apparatusfor Preparing, Feeding, and Burning Pulverized Fuel, of which thefollowing is a specification.

My invention relates to a new and improved method of and apparatus forpreparing, feeding and burning pulverized fuel, and ithas for its objectthe improvement of the method and apparatus now in use. It is one of theprincipal objects of my invention to provide new and improved methodsand apparatus whereby the coal or other fuel may be dried to a suitableextent while passing through the pulverizing mill and may be deliveredto the furnace in such a condition that it will be completely consumedinv the combustion chamber of the furnace so" as to utilize fully theheat element of the fuel. To this end, it is the object of my inventionto provide an arrangement of parts by which hot gases from the flue,preferably with the addition of air, shall be used for floating thepulverized particles from the pulverizing mill in lieu of the use ofatmospheric air alone for this purpose.

The preferred means by which I have accomplished my objects areillustratedin the drawing and are hereinafter specifically described-That which I believe to be new and desire to cover by Letters Patent isset forth The drawing illustrates a mill connected up for feedingdirectly .to a furnace, with means for supplying the flue ases to the.mill, all shown more or less diagrammati- Cally. a

I ed therein, and

In the drawing, 10 indicates a furnace with a boiler 11 of any suitabletype mountprovided with a flue 12 in an desired position with respect tothe boiler 11 and the firebox of the furnace.

' In the drawing, I have indicated a mill of the impactior beater t e,but it will be understood that I do not esire to limit myself to thisparticular form of mill, except)- so far as such specific form may beclaimed. In the construction illustrated, coal or other fuel to bepulverized is fed by any suitable means to a hopper 13 from which it isfed by feeding means 14 of any suitable type into the beater chamber 154An air inlet 16 opens into the mill on the feed side of the chamber 15,the air inlet being provided with a damper 17. Within the beater chamher15 are mounted a plurality of heaters 18 of any suitable type adapted tobe operated by a shaft 19 passing through the beater chamber and drivenby a motor 20. In the construction shown, the shaft 19 is supported bybearings 21, the beaters 18 being mounted upon and supported by theshaft 19. In the construction shown, the feeding device 14 is alsodriven from the shaft 19 by suitable connecting means of any approvedtype which it is believed to be unnecessary to describe in detailherein. The mill as illustrated comprises a conical extension 22 at thedelivery side of the chamber 15, a beating and regulating device 23being mounted upon the shaft 19 within the extension 22, as is usual inthe mill of this type. The conical extension 22 communicates at itsdelivery end with a fan chamber 24, within which is mounted a fan 25 ofany approved type. The fan chamber 24 is connected by a conduit 26'Witha burner 27 opening into the firebox of the furnace 10.

It has been found in practice, in the use of a mill of this type, thatunder certain circumstances it is difficult to burn pulverized coal of ahigh moisture content.

The presence of the moisture within the firebox of the furnace is notitself a disadvantage, -and does not serve to prevent the full andcomplete consumption of the pulverized fuel, except in the case wheresuch moisture is contained in the particles of the fuel. On thecontrary, under certain conditions the presence of the moisture withinthe combustion chamber of the furnace is a distinct advantage, inasmuchas it has a tendency to assist in preventing the formation of slag. p

For the purpoe of separating the molsture from the particles of thepulverized coal, or

other fuel,,but without any attempt to remove the moisturefrom thestream of fuel as it is fed to the furnace, I have provided a connectionbetween the flueportion of the furnace and the pulverizing mill forcausing a current of hot flue gases'to flow from the fine to the beaterchamber of the mill. This connection in the construction shown is in theform of a conduit 28 connected at one end with the flue 12 of thefurnace and at the other end with the air inlet 16 of the mill, a damper29 being provided in the conduit 28 for controlling the amount of gaspermitted to enter therethrough.

As will be readily understood, in the use of the mechanismasillustrated, by closing the damper 17 completely" and opening thedamper 29, the flue gases may be utilized alone for the flotation of thepulverized particles of fuel intothefurnace 10. In such case, it wouldbe necessary that the air necessary for combustion be admitted to thefurnace from some other source. It will be understood also that by.closing the damper 29 completely and opening the damper 17, theapparatus can be used without the admission of any flue gases, the fuelbeing carried to the furnace *by the air alone. In practice, the dampers17 and 29 can be regulated with respect to each other for Varying in anydesired way the proportion of air and hot flue gases, depending upon theconstruction of the furnace, the moisture content of the coal or otherfuel as delivered to the hopper 13, and upon other conditions in anyparticular case. In the preferred operation of the furnace, a sufficientsupply of hot flue gases is to be admitted through the pipe 28 forattaining the desired drying effect upon the fuel during its movementthrough the pulv'erizing mill and through the conduit 26.

In some instances, I have found that by the. use of a suitable supply ofhot flue gases leaving the flue at a temperature of about 500 degreesFahrenheit the moisture content of coal has been reduced from aboutfourteen percent to three or four percent, the fuel being changed from acond1tion.in

which it was difficult to burn to a condition in which it burnedreadilyand was completely consumed Within the combustion chamber of thefurnace.

It will be understood that while I prefer to employ the combination ofpar-ts as illus trated in the drawing, I do not desire to limit myselfto the use of this particular arrangement and construction, except sofar as the same is specifically rclaimed, since it is evident thatchanges might well be made in the arrangement andconstructioriwithoutdeparting from the spirit of my invention.

I claim: i

1. The method of preparing, feeding and burning fuel, which comprisesfeeding the fuel to a puiverizing mill, causing a current of hot gasesfrom the flue of the furnace to pass through the mill, admi the hotgases to the mill, controlling the amount of air admitted in relation tothe amount of hot gases, and feeding the fuel tting air with byflotation on the current of air and gases from the mill to the furnace.i

2. The method of preparing,'feeding and burning fuel, which comprisesfeeding the fuel to a pulverizing mill, drying the particles of fuelduring the movement through the mill by the introduction into the millof hot gases from the flue portion pf the furnace, admitting air withthe hot gases to the mill, controlling the amount of air admitted inrelation to the amount of hot gases, and feeding the fuel to the furnacewith the air, the partially cooled gases, and the moisture liberatedfrom the particles of the fuel.

3. An apparatus for preparing, feeding and burning fuel, comprising afurnace, a pulverizing chamber, means for feeding fuel to said chamber,adjustable means for admitting air to said chamber, and means forcausing a draft of'hot flue gases from the furnace to mix with the airand flow through with the air and flow through the chamber for carryingthe puh'erized fuel, into the furnace, and means for controlling theamount of air with relation to the amount of hot gases in said current.

5. An apparatus for preparing, feeding and burning fuel, comprising afurnace, a pulverizing chamber, means for feeding fuel to the chamber,means for admitting air and hot gases to the chamber comprising an airinlet, and a conduit leading from the flue portion of the furnace, adamper in the air inlet, a damper in the conduit, a conduit connectingthe chamber withthe fire box of the furnace, and means for causing acurrent of-air and hot gases to flow through the chamber and the latterconduit for carrying the pulverized fuel to the furnace.

6. An apparatus for preparing, feeding and burning fuel, comprising afurnace, a pulverizing chamber, means for feeding fuel to the chamber,means for admitting air and hot gases to the chamber comprising an airinlet, and a conduit leading from the flue portion of the furnace, aconduit connecting the chamber with the fire box of the furnace, meansfor causing a current of air and air inlet and in the first mentioned'conduit for regulating the relative proportions of the air and hot gasesadmitted to the chamber.

LABS H. BERGMAN.

